Burner control apparatus



Aug. 7, 1945. Q w HAHN I 2,381,215

BURNER CONTROL APPARATUS Filed Jan. 12, 1942 INVENTOR. 0 7' TO W. HA /v A T TOR/VEY with the upper coils 3 passing directly over the Patented Aug. 7, 1945 UNITED STATES PATENT OFFICE BURNER. COZfiifAPPfiBATUS I Otto W. Hahn, San Francisco, Calif., amlgnor to aim, massa e...

Application January 12, 1942, Serial st. ssue 4 Claims.

This invention relates to burner control apparatus of the type employing a thermostat in connection with pipe coils in which 'a fiuid is heated, such for instance as gas water heaters, and the objects of .the invention are to provide 5 improvements in such apparatus which will greatly reduce the costof construction and be more emcient and quicker in response to'heat variations and prevent injurious overheating of the coils.

Other features and advant 'es of the invention will appear in the followi g description and accompanying drawing.

In the drawing Fig. l is an elevation of atypical installation showing my improved control apparatus built in a pipe coil type gas water heater.

' type.

In the showing ,of the drawing (Fig. l), the heating equipment includes a gas burner I, a heat transmitting shell 2, above and embracing the burner, a tube or pipe coil 3 wrapped about the shell in good thermal contact therewith, and

upper end of the shell through a series oi heat transmitting sheet metal fins 4 which are thereby suspended in-the ascending hot gaseous products of combustion, and conduct the heat directlyto the pipe coils and to the water or steam therein to be heated. Spaced outside of the pipe coils is an outer casing shell as indicated at 5.

The gas water heater shown is of well known construction and is only to illustrate the application of myinvention, as it may take the form of any heater having any number of pipe coils or fiuid carrying heating tubes arranged'in any manner providing that some of them are q pped with fins immersed in the heating zone.- -In the heater illustrated, the fiow of water in the coils is from the bottom of the coil upward, as denoted by the arrows,- and the fiow is controlled in any ofthe well known ways, not shown, as not being involved in the present invention.

Broadly, my invention comprises mounting an expansible thermostat directly through and in thermal contact with the fins and thereby making the heat changes in these fins the principal factor in operating the thermostat, and by it the fuel control valve supplying the burner.

Specifically, the thermostat and its valve embraces special construction to eifectively carry out the invention, and details of my preferred construction are shown in Figs. 3 and 4.

In Fig. 2 the thermostatic element is indicated generally as a long pipe or tube 0 tightlyembraced by the heater pipe fins l directly through which it passes. These fins are preferably of copper, as also is the tube 6, and they are preferably formed with flanges around the holes through which the tube 6 passes so as to form a tight thermal fit thereagainst, and may be brazed in place for better heat transfer, and of course the same fins extend to similarly embrace one or several of the heating coil tubes, or pipes 3' as indicated.

Tube 6 is secured at its inner end as by welding or threading as at I to the hub 8 of one portion 9 of a valve body Ill, and at its outer end it is closedas by a common pipe cap screwed over it, or by drawing or welding the copper tube to-.

gether as indicated at 6' in Fig. 3, and thickened inside as by a button [I of metal 'weldedin place and having a threaded hole It in its center, and into which hole is screwed the outer end ,of a metal rod II of less expansibility than the copper tube 6, preferably a metal of the nature of Invar, so that when heated the cop'pertube will elongate considerably, relative to the rod. g

This rod I3 is spaced within the tube 0 and may have a loose filling of asbestos or a loose sleeve of asbestos It around it to further reduce the heat transferred to it from the tube when heated, although this feature may be dispensed" outer side of a spring sheet metalspider II which spreads out in front of disk it, and is supported at the outer ends of its arms on a shoulder ll formed at the bottom or a counter-bore It in member a, and within which counter-bore is a Y ring 2| formed at its outer margin with a V- shaped rim 2: bearingagainst the inner side of the spider [8 along a circular line outward from v the circular line of contact of the rim I! of disk' II at the opposite side of the spider. Ring 29 is touching but not tightly clamped against the spider I9;

The spring sheet metal spider may have any number of arms, and the form of the arms may be varied, but a spider of about 8 arms as shown in Fig. 4 has been found satisfactory.

Valve body member 9 is recessed as at 23 to receive the flange 24 of the main portion I! of the valve body, and secured thereto as by screws 25. Body member 9 is provided with threaded inlet and outlet ports 28 and 21', and a valve pas sage 29 adapted to connect the two ports when not closed off by a valve disk 29 which closes on a seat 99 surrounding passage.

Valve disk 29 is formed with hubs on both sides 3 l, 92, with the latter being elongated and slidably supported in a bore formed in a closure bonnet 94 screwed into the valve body member III as indicated. Hub :2 is formed with a groove 35 along one side-into which the end of a pin 8. projects so that the hub cannot be revolved in the bore, although it is free to slide longitudinally. Bore 39 extends clear through the bonnet II, and is closed by a threaded plug 91. I

Valve disk 29 is urged toward its seat by a coiled compression spring 39, and its hub is drilled centrally, and slidably positioned in the hole is a rod 39 bearing at its outer end against the inner side of spider l8, and impinged at its inner end by a screw 40 threaded into the inner end of hub 32. Screw 40 is preferably a snug fit so that it will stay in adjusted position, and it is accessible with a screwdriver when plug 31 is removed. Screw l9 and rod 39 may be one piece if desired, as rod 39 only acts as an extension of the screw, and

forms as it were, an extensible valve stem along which the position of the valve disk can be adjusted by turning the screw.

the burner.

' In the showing of the drawing, valve 29 may be directly on the gas or other fluid fuel passage for A vent 42 preferably connects the thermostat tube space to the valve space.

In considering the construction described, it will be seen to operate quite differently either from such a linear expanding thermostat placed within the hot water pipe or space of a water heater, for such thermostats would not quickly respond to an absence of water in the pipe until the pipe was overheated and destroyed, whereas with the present construction, the fins being in thermal contact with the water pipes or tubes correctly rep resent the temperature of the pipes as well as the relative temperature of the water in them under normal conditions of water heater operation, if however, the supply of water should cease and hot water were drawn ed to leave the pipes empty, or partially, or steam were formed, so their temperature would rise very quickly and likewise that of the fins, the expansible thermostatic element 6 being directly connected to the fins would operate to at once shut off or turn down the burner flame, and vice versa, and therefore provides a much more sensitive apparatus yet of sufficient may readily be made without departing from the The valve disk shown seated in Fig. 3 presumes the thermostatic elements 9 to be over-heated spider i9 and arch, it inwardly as indicated by the dotted line l9, and thereby hold the valve open.

The degree of'opening of the valve when the aptparatus is cold, or rather the degree 0!. heat which will be required to permit the valve disk to close when the thermostatic element-is too hot, is determined by the position of the valve disk along the stem I9 as set by the adjustment of the screw.

.In such apparatus wherein a linear expansible element is used mechanically, it generally opcrates directly on the valve stem, and therefore produces very little motion unless the element is extremely long, but by the use of the spring spider, the arms provide a radially arranged groupof motion amplifying levers i'ulcrumed at their outer ends under annular rim 2!, and with the operating force applied by annular rim ll a very short distance from the fulcrum'pointnio that a slight linear motion or relative motion of rod II at once produces 'a greatly ampliiled'motion of the valve and thus eilects immediate and direct large main fuel valve control from minute temp rature changes in the thermostatic element without the use of mechanical or electrical relays or pilot valves, although itis manifest that if desired the device may be'made very small and with a small flow through its valve used to control mode of operation above setout.

I therefore claim:

1, In a burner control apparatus for a fluid heater, a fuel burner arranged to create a heating zone passing upwardly above the burner, a heating tube through which the fluid passes positioned in said heating zone and provided with a plurality of spaced h'eat conducting sheet metal fins directly embracing and projecting therefrom, fuel feed controlling means for said burner comprising a thermostat arranged adjacent, said heating tube also in thermal contact with a plurality of said sheet metal fins, and means operated by said thermostat operating said fuel feed controlling means, said heating tube extending transversely or crosswise of and within said heating zone, and said thermostat being substantially spaced from and above said tube.

2. In a burner control apparatus for a combustible fluid fired water heater, a fuel burner arranged =to create a heating zone passing upwardly above the burner, a water heating tube'th'rough which the water passes provided with a plurality of spaced heat conducting sheet metal flnsdirect- 1y embracing and projecting therefrom arranged -in the path of thehot gasous products of comheater, afuel burner arranged to create a heating zone passing. upwardly above the burner, a plurality of parallel runs of spaced heating tubes through which the fluid to be heated passes positioned in said heating zone, a plurality of spaced sheet metal heat conducting fins extending transversely of and directly embracing said tubes and through which fins all of said tubes extend in thermal contact therewith, and fuel feed controlling means for said burner comprising a thermostat provided with a main heat expansible element in the form of an elongated linearly expansible tube extending transversely through snugly fitting openings in and in thermal contact with a plurality of said fins adjacent one of said heating tubes, and means operated by said thermostat operating said fuel feed controlling means, said heating tubes extending transversely or crosswise of and within said heating zone, and said thermostat being substantially spaced from and above said heating tubes.

4. In a burner control aparatus for a liquid heater, a fuel burner arranged to create a heating zone passing upwardly above the burner, a liquid circulating h'eating pipe positioned in said heating zone provided with a plurality of spaced sheet metal heat conducting fin extending transversely of and directly embracing the pipe for conducting heat thereto, a thermostatically operated valve for controlling fuel feed to the burner of the heater comprising an elongated thermostat made of two cooperative dissimilarly expansible members passing through aligned openings in a, plurality of said sheet metal fins adjacent said pipe and with its most expansible element in direct thermal contact therewith, said heating pipe extending transversely or crosswise of and within said heating zone, and said thermostat being substantially spaced from and above said heating pipe.

OTTO W. HAHN. 

